PH Question?

[ghost427]

Is PH lower in the morning when the lights first go on, than in the evening?

[Randy Holmes-Farley]

Yes.

Unless you are doing something unusual (like timed limewater additions or a reverse light cycle refugium), the pH will be lower in the AM, and then decline during the day as CO2 is used by photosynthetic organisms. At night, respiration by all organisms produces CO2, and that drops pH.

Perfect aeration will reduce or eliminate the day/night swing, but that is not necessary, IMO